My prior United Kingdom patent application, GB 2 094 653 A published on Sept. 22, 1982, discloses parallel filters which are alternately communicated with two separate manifolds by means of a valve which passes filtrate selectively from one of the manifolds to a pump and discharge ducts. When sufficient liquid has been fed to the filter tank, the pump is operated to draw filtrate from one of the manifolds. When a vacuum gage senses a reduced flow rate from one manifold, the timer controlled valve moves to draw filtrate from the other manifold and actuates a second valve to cause a pulsed back flow in the first filter set to clean the filter media. If the liquid level in the tank falls, a third valve diverts the discharge from the pump back into the tank. Sludge is removed from the bottom of the tank by simply draining off or by a conveyer. The filter units include filter cloth covering an expanded metal panel fitted onto a manifold coupling. The filter unit is sealed against the manifold by a ring seal compressed under the weight of the filter unit or by clamps for the filter unit. The external surface of the filters can be fitted with flat or curved louvers. A magnetic bar can also be provided at the top of the filter units so that they can be removed by a magnetic hoist. A fourth valve mechanism in the manifold is opened automatically when the filter is fitted on the manifold.
My prior U.S. Pat. No. 4,591,903 discloses a suction-type filter machine having a plurality of filter leaves. Each filter leaf includes a core panel of egg-crate type walls defining transverse passageways through the panel and openings through the walls to provide vertical, horizontal and longitudinal passageways for filtrate flow. The filtrate is drawn through the filter medium enwrapping the core panel by a suction pump. A conduit conductor encloses an edge portion of the core panel for communicating the filtrate flow from the interior of the core panel through a manifold connected with the suction end of the filtrate pump. The effluent to be filtered is charged into the tank of the filter machine from above the filter leaves or units, so that there is a continuous downward flow of polluted liquid and its entrained solids from the input opening to the solid discharge portion of the filter machine. The filter machine can continuously filter a very large volume of polluted liquid and simultaneously separate the solids therefrom for discharge to the settling tank portion of the machine. The relatively close spacing between the side-by-side proximity of the filter units, one with another, is governed by the diameter of the filter medium covered discharge tube or conduit mounted on and at one end of the filter core panel. The filter machine has substantially zero flow of liquid below the filter units, thereby allowing the solid particulates to settle readily to the bottom of the filter tank. The filter leaf core panels can easily be removed from the machine by merely picking them up from their positions of rest upon the supporting manifolds in the tank.
My prior U.S. Pat. No. 4,579,656 discloses a leaf-type filter system, in which a suction pump is employed to pump filtered fluid from a series of individual filter leaves connected to an individual leaf chamber via a fluid coupling located above the surface of fluid being filtered. The couplings are of inverted U-shape and have a sliding sealing fit with the vertical outlet tube of a filter leaf and a vertical receiving tube mounted in a manifold or header external of the main filter tank. Identical individual filter leaves are formed in a rectangular configuration of relatively narrow lateral thickness. Along one vertical side edge of the leaf, a cylindrical coupling tube is mechanically attached to the core of the leaf and is in fluid communication with the internal chamber defined by the leaf core to constitute the outlet tube for conducting filtrate from the leaf. The outlet tube projects upwardly above the horizontal upper surface of the rectangular leaf and, when located in the filter tank, the upper end of the outlet tube projects above the surface of fluid to be filtered contained in the tank. The diameter of the leaf outlet tube is made larger than the lateral thickness of the leaf. The interchangeable leaves are placed into the tank with the outlet tubes of alternate leaves at opposite sides of the tank. Vertical guides on the inner sides of the tank are employed to locate the outlet tubes laterally along the walls. The relatively thin, vertical end edge of one leaf is engaged between the outlet tubes of the two adjacent leaves in side-by-side relationship with a spacing between the leaves determined by the amount by which the outlet tube diameter exceeds the lateral thickness of the leaf itself. A closed manifold is located on opposed outer sides of the main filter tank. Receiving tubes opening into the interior of the manifold project upwardly through the upper wall of the manifold and are located to be in alignment with the respective outlet tubes of the filter leaves. The individual outlet tubes of the filter leaves and the associated receiving tube of the adjacent manifold are detachably coupled to each other by an open-ended coupling tube of inverted U-shaped configuration. The opposed ends of the U-shaped coupling tube are dimensioned to slidably fit into the upper ends of a filter leaf outlet tube and its associated receiving tube to thus place the interior of the manifold in fluid communication with the outlet tube of the leaf. A suction pump connected to each manifold establishes fluid flow of filtrate from the leaves to the outlet tube, coupling tube and manifold for transfer to a collection point. The individual leaves are easily removed and replaced by manually lifting the coupling tube to slip it off the outlet tube of the leaf and the receiving tube of the header, at which time the leaf is available for manual removal.
Many of the known leaf-type filter machines have short operating cycles because the solid particulates must collect on the filter medium, clogging the openings, which results in the rapid build-up of a cake on the filter and correspondingly reduces the amount of filtrate flow. Tremendous amounts of time are consumed in shutting down the filter machines and cleaning the cake from the filters. The present invention provides increased operating cycles with more efficient filtration characteristics. The present invention is capable of filtering submicron and larger particles from large volumes of fluid in a relatively small compact apparatus. The present invention also provides relatively light weight filter panels that are inexpensive to manufacture and maintain. The filter panels of the present invention also include the feature of easily replaceable filter media sheets.